1. Field of the Invention
The present invention relates to an automatic annular valve including a valve seat, a valve guard, and a valve element arranged in a reciprocating manner between the valve seat and the valve guard, whereby the valve element is formed of a sealing element made of concentric sealing rings sealingly cooperating with the valve seat, and including further a synchronizing plate arranged on the opposite side of the sealing rings facing the valve seat.
2. The Prior Art
In case of annular valves, especially for sealing purposes, the valve element can be designed having a valve plate provided with either a row of annular openings or a plurality of separate concentric sealing rings. A design having a valve plate can be seen in EP 300 989 A1, for example, which describes a valve element including a soft locking plate and a hard guide plate lying directly against it. Moreover, a damping plate is provided in the valve. When using concentric sealing rings, it is already known in the art to additionally use a synchronizing plate which rests against the sealing rings and is moved in conjunction with said rings to synchronize and dampen the movement of the individual sealing rings. The sealing rings and the synchronizing plate thereby form the valve element together whereby the sealing rings and the synchronizing plate are, however, only loosely placed against one another. The damping effect of the synchronizing plate is the result of the proper weight of the synchronizing plate, on the one hand, or the synchronizing plate can also be biased by a spring, on the other hand. The design including a synchronizing plate offers additionally the advantage that large and robust springs can be selected which can be affixed at the center of the synchronizing plate which is formed of radial cross pieces and openings extending in circumferential direction. For example, an annular valve of this type is disclosed in AT 391 928 B or EP 345 245 A2. An auxiliary damping plate may still be provided in the annular valve as shown in EP 345 245 A2 as well. However, such a damping plate acts independently from the sealing element and is arranged at a distance apart from the sealing element and it only serves to further dampen the movement of the ring opening essentially by its proper weight after a specific opening distance of the valve.
Due to their different employment which is intended the concentric sealing rings and the synchronizing plate place different requirements on the material to be selected. The sealing rings cooperate with the valve seat of the annular valve and achieve the function of sealing whereby the sealing rings sealingly cover the openings of the valve seat in the closed condition of the valve. The synchronizing plate is stopped by the valve guard at the end of the ring opening movement. Even though there exists a certain damping effect, the synchronizing plate impacts the valve guard at high velocity with each opening, which naturally stresses the synchronizing plate correspondingly. Besides, the synchronizing plate must be correspondingly stable against deformation to be able to synchronize the sealing rings.
However, since the sealing rings and the synchronizing plate lie directly against one another, their type of material cannot be selected solely based on the required function and their contact to one another has to be considered in view of wear upon both parts. The choice of material is therefore not optimal under certain circumstances and concessions have to be made relative to functioning since favorable materials in terms of wear could result in a very bad combination of materials.
In addition, experience shows that sealing rings can slowly cut into the synchronizing plate during operation, based on the frequent change in loads and particularly also based on the high switch-over frequency, especially if said synchronizing plate is made of synthetic material. This can be especially observed when the sealing rings as well as the synchronizing plate are made of a synthetic material, especially fiber-reinforced synthetic material. In this case, the sealing ring and the synchronizing plate even cut into each other. This leads to an increased wear of the synchronizing plate and/or the sealing rings, and to an unacceptable damage to these parts with time, impairing the sealing function so that these parts have to be often replaced.
It is therefore the object of the present invention to further develop an annular valve of the aforementioned type in such a manner that the wear of moving parts of the valve element in the annular valve is reduced.